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  1. #1
    Join Date
    May 2003
    Posts
    792

    4th axis- planetary vs harmonic?

    I`m interested in adding rotary 4th axis to DIY-CNC Router Table Machine.

    Some people use planetary gearhead for that purpose, others claim harmonic drive is better because it`s zero backlash. Has anyone here had any experience with harmonic drives?


    Thanks

  2. #2
    Join Date
    Dec 2004
    Posts
    518
    Quote Originally Posted by walter
    I`m interested in adding rotary 4th axis to DIY-CNC Router Table Machine.

    Some people use planetary gearhead for that purpose, others claim harmonic drive is better because it`s zero backlash. Has anyone here had any experience with harmonic drives?


    Thanks
    Walter,

    Hi! There are a few discussions about this going on right now-look at some of the 5-axis threads. Personally I plan to use the harmonic drives-for exactly the reason you meantion. I suppose it really depends on what you are planning on making (required tolerances, etc.) on the one hand and cost on the other. At any rate, take a peek at the other threads-it may help. Good luck!

    Lance

  3. #3
    Join Date
    May 2003
    Posts
    792
    Thanks Evodyne, good info.

    I read about harmonic drive accuracy and low backlash. I`m a bit concerned about longevity... Some estimastes say 3000 hrs vs 30000 hrs with planetary gear based systems. Seems like a big difference, harmonic drives are not cheap..

  4. #4
    Join Date
    Dec 2004
    Posts
    518
    Quote Originally Posted by walter
    Thanks Evodyne, good info.

    I read about harmonic drive accuracy and low backlash. I`m a bit concerned about longevity... Some estimastes say 3000 hrs vs 30000 hrs with planetary gear based systems. Seems like a big diffefence, harmonic drives are not cheap..
    You may want to look at Harmonic Drive Technology's site for more info on expected life.

    Lance

  5. #5
    Join Date
    May 2003
    Posts
    792
    Yeah... They mention the 3000 hrs number too. And say that actual life would be 5 times longer. Not bad.

    By the way, Evodyne. Do you have any good harmonic drive source?


    Thanks

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